Re: Fuel Injection Modifications

[jwit6@xxxx]

--- In dmcnews@xxxx, "Scott Mueller" <scott.a.mueller@xxxx> wrote:
> Can you post some pictures to the vault?
> What was the cost of the components?
> Can you use the stock fuel pump?
> How about writing a how to article for DMCNEWS, perhaps the 
Moderators can
> add a section in Tech for Modifications.

DMC-12 Bosch CIS to Multiport EFI conversion.

Bosch CIS systems are almost entirely based on 1960's era technology, 
and rely on a mechanical air flow meter to monitor engine load and 
regulate fuel delivery. Most people agree that these air flow meters 
pose a formidable intake restriction and rob anywhere from 10% to 15% 
of available engine horse power. HP is directly related to the 
volumetric efficiency of the engine, and the PRV can move a bit more 
air when the CIS air flow meter flap is not in the way.

I used the Racetech Simple Digital Systems (www.sdsefi.com) EM3D. 
There is no need for a laptop for programming. It has a well written 
easily understood technical manual and documentation, a nice 
intelligent website, and a growing user community with a forum for 
SDS at http://network54.com/Hide/Forum/150383 . There is plenty of 
friendly and knowledgable technical expertise available from both 
Ross and Barry at Racetech. Plus the SDS EM3D is attractively priced.

Since I've never driven a CIS powered Delorean, I can't say anything 
about my impressions concerning potential horse power increases. Also 
I've not put the car on a dyno. All tuning ( of which very little has 
been required ) has been done on the street.

Here are the details about what I used, and how it was done.

The injectors I used are low impedance Bosch part number 280-150-812, 
which also cross reference according to Borg Warner to 280-150-828 
and 280-150-829. Borg Warner part number 57172. Chrysler part number 
4467050, INP-012, J0260675, MD116218, MD132249, MD141131, MD156661, 
and MD157740. They can be found in the Dodge/Chrysler/Plymouth 
Mitsubishi 3.0 V6 from a Dynasty 88-92, Caravan 89-91, Lebaron etc. 
They are also listed as the same injectors that were used in the 
Eagle Premier 3.0 Z7X-715 PRV V6 91-92. I choose the Bosch which are 
characterized by a concave aluminum injector tip. The junk yards are 
full of them.

The Bosch electronic injectors fit the existing 14 mm CIS injector 
ports which is very nice. Tips are recessed 20 MM above the intake 
tract within the 12 mm lower diameter of the injector port. The 30 
degree injector spray pattern does not seem to impinge on the lower 
port. Mine came from the scrap yard for $10.00 a piece and had to be 
cleaned and tested. 

Low impedance Injectors (2.5 ohms) can be tested with mineral 
spirits, a standard fuel injection pump, filter, 43 psi regulator, 
and 12 volts DC with an appropriate ballast resitor (like from a 
914/4 Porsche), or when 3 or more injectors are run in series. For my 
used injectors I ran and flushed them backwards first to clean the 
internal filters. I tried to run no more than 30 seconds at a time 
and avoided overheating the injectors. I understand Bosch injectors 
can take a lot of abuse. I checked for leaks and an even spray 
pattern. I've read that leaks should be no more than 2 drops per 
minute. This is also a good way to find how much an injector actually 
flows. Injector flow rates influence ECU programming pulse width 
values, and flow rates are NOT published. So for other applications 
you've got to figure out what you've got before you set up your 
baseline ECU program values. The 280-150-812 Bosch injectors work 
very nicely with reasonable duty cycle values in the normally 
aspirated PRV 2.8. Racetech was very helpful with this.

The fuel pressure regulator is from a Nissan 280 ZX,1981 which runs 
at 43 psi. Beck Arnley 158-0091 or Borg Warner 21710 . Also available 
at Autozone for about $43.00. It uses 5/16 inch barb fittings and 
mounts nicely to the forward right corner of the air flow meter 
housing. You can run vacuum from the line that went to the old 
Control Pressure regulator.

The Fuel Accumulator you can remove or keep. It doesn't matter.

I kept the Original Delorean Bosch fuel pump, delivery lines to the 
engine compartment and return line plumbing.

I kept the original fuel filter and ran R9 MPI fuel line hose form 
the fuel filter banjo fitting directly to the front LH brass hose 
barb fitting on the new left hand fuel rail.

I removed the CIS Control Pressure Regulator, the delay valve from 
the Control pressure regulator vacuum line and routed the line to the 
280 ZX fuel pressure regulator.

The Cold Start Valve was removed. You can plug the end of the cold 
start enrichment tube, or make a simple fitting to run the MAP sensor 
from. This is a nice place to pick up the MAP because it is balanced 
to all cylinders and orificed at the factory. Otherwise there is 
another factory 1/8 inch NPT fitting available at the right rear 
corner of the intake manifold.

I removed the Frequency Valve and optionally you can remove the 
Delorean Bosch Lambda ECU. 

I removed the upper half of the airflow meter housing, the fuel 
distributor, gutted the upper air flow meter housing, and plugged all 
the openings left after the fuel distributor, meter flap and pivot 
had been removed. Then I reinstalled the gutted upper air flow meter 
housing. If you're looking for an easier way to do this you can 
simply remove the screw that holds the round air meter flap to the 
pivot arm and leave everything else in place. Then all you've got to 
do is plug the hole where the fuel distributor used to mount. This 
way you don't even have to remove the meter housing.

I used a standard GM V-6 1 bar, three wire map sensor. Borg Warner # 
EC1602, or the one available from Racetech. They are almost all the 
same. Mounted with the orifice facing down. 

The Air Temp Sensor was provided by Racetech, and is mounted in the 
factory original 1/8 inch NPT plug located in the left rear corner of 
the intake manifold. 

The Engine Temp Sensor is also provided by Racetech. I removed the 
thermostat drain plug located in the water pump thermostat housing 
directly below the thermostat on the engine side of the thermostat 
and drilled and tapped the plug for 1/8 inch NPT. 

For the Distributor and Advance, I retained the existing vacuum 
advance solenoid, micro switch on the throttle body and the entire 
ignition system. The PRV is an ODD FIRE V-6, so tach signals from the 
Bosch ignition ECU to the ignition coil are uneven. The Racetech SDS 
ECU is driven off of this signal, which is picked up at the coil 
terminal # 1. The SDS EM3D ECU is a "batch" injection system. 
Injectors fire at the same time, not sequentially, and the fuel 
charge hangs around in the intake manifold by the intake valve until 
it's needed. Odd fire does not seem to be a problem since the 
programmed RPM values I'm using for most of the RPM ranges are the 
same or very flat. RPM values at the SDS ECU do seem to hunt a bit 
sometimes but never more than 3 RPM ranges. If you're really 
concerned about triggering the SDS ECU off of the ODD FIRE coil, then 
you can opt to install a HALL effect triggering system off the crank 
pulley. Mine runs very nicely off the tach signal.

I kept the original Bosch O2 Lambda Sensor. The Racetech SDS ECU can 
be programmed to run in closed loop lambda mode between high and low 
map values and high and low rpm values that you can set, using the 
existing single wire or a newer 3 wire O2 sensor. Lambda closed loop 
can adjust your baseline values by up to + - 25%. I have CL LOW RPM 
LIMIT set to 1500, and CL HI RPM LIMIT set to 4500 (70% of redline). 
CL MAP HI is set to -6.72. CL MAP LO is set to -15.2. Talk to Barry 
or Ross at Racetech.

You should retain the Bosch Idle Speed Motor and ECU if you can. 

My fuel rails are 1/8 inch NPT brass pipe. Four 4 inch nipples cut to 
the correct injector port center to center distances and threaded 
with a 1/8 inch NPT die, then assembled with 6 brass Tees. Four hose 
barbs, one at each end of the 2 fuel rails connect to 5/16 MPI R9 
fuel injection line. The line runs from the filter to the LH front 
rail barb, the LH rear rail barb across the rear of the engine to the 
RH rear rail barb, and then from the RH front rail barb to the fuel 
pressure regulator. Rails are held in place by fabricated 3/4 inch 
wide steel brackets secured to the valve cover bolts. Fuel return is 
off of the right front fuel rail barb directly to the 280 ZX fuel 
pressure regulator. 

I was able to keep all of the existing Air Cleaner and pre-heat 
system. The fuel rails are small enough to allow the original air 
cleaner and intake pre heat plumbing to be retained. Air filter 
housing clips closest to the engine had to be relocated to the sides 
of the airfilter housing to avoid interferance with the new fuel 
rail. I used safety wire through 1/8 inch vacuum line wound to the 
correct length with the original clips, and then clipped them on to 
the upper side edges of the air filter housing. 

The Throttle Position Sensor is a 3 wire Potentiometer type. It is 
driven by the existing horizontal throttle pulley by simple heater 
hose and a machined aluminum fitting that mates with the tabs on the 
switch. An aluminum and sheet metal bracket supports the switch. My 
switch is off of a Ford 4 cyl courtesy of the scrap yard. Almost any 
will work. Racetech can provide them in clockwise or counter 
clockwise configurations. Delorean uses clockwise. 

I mounted the SDS ECU right behind the driver seat where you'll find 
the 3 existing OEM ECU's. Since I abandoned my Idle Speed Motor, I 
removed the black Bosch idle speed motor ECU which sits right on top 
of the metal mounting frame. The SDS ECU fits quite nicely. You can 
also remove the Bosch Lambda ECU if you like, and rearrange the 
remaing ECU's to make everything fit. Grounds are taken from the 
metal mounting frame itself, and switched power is picked up through 
a 1 amp fuse (which you must supply) to the main relay behind the 
passenger seat. Hot switched power for the injector harness is taken 
off of the HOT side of the ignition coil ballast resistor (white 
wire,upper right spade connector).

The car passed Ohio Emissions Testing last week. I'll post some 
pictures once I figure out how it's done.
Jim Witherspoon
Vin #6147